So step one is use a small race like gnome or goblin, once your a small race and you are at least level 3 you can use your steel defender as a mount as per small race rules when it comes to mounts needing to be one size larger.
once you have your steel defender mount you have a bunch of combat options, if you pick up crossbow master you can use a hand crossbow to launch up to 3 attacks, then you can couple ot with sharpshooter and take a level of fighter for the archery feature (or 2 levels if you want to action surge).
With the steel defender mount you'll have a movement speed of 40 but you wont be able to move on your turn and the artificers class guarantees at least up to a +2 weapon.
So step one is use a small race like gnome or goblin, once your a small race and you are at least level 3 you can use your steel defender as a mount as per small race rules when it comes to mounts needing to be one size larger.
once you have your steel defender mount you have a bunch of combat options, if you pick up crossbow master you can use a hand crossbow to launch up to 3 attacks, then you can couple ot with sharpshooter and take a level of fighter for the archery feature (or 2 levels if you want to action surge).
With the steel defender mount you'll have a movement speed of 40 but you wont be able to move on your turn and the artificers class guarantees at least up to a +2 weapon.
Try using a hollow Steel Defender as armor, or a single person, personel carrier. :)
Watch your back, conserve your ammo,
and NEVER cut a deal with a dragon!